Glutathione depletion-induced neutrophil apoptosis is caspase 3 dependent

Resolving inflammation is a vital step in preventing the persistence of inf lammatory disorders. Neutrophils play a major role in tissue damage associa ted with an inflammatory response. Their death by apoptosis is central to t he final resolution of this response. Thiol depletion with diethylmaleate ( DEM) or diamide represent important triggers for neutrophil apoptosis. The mechanism by which this process occurs remains unknown. The apoptotic casca de is associated with a number of cellular changes, including caspase activ ation and mitochondrial permeability. The aims of this study were to determ ine the role of mitochondrial permeability and the caspase cascade in thiol depletion-induced neutrophil apoptosis. Total cellular glutathione was red uced by DEM and diamide. This reduction was associated with neutrophil apop tosis and an increase in caspase 3 activity. The effects of DEM were blocke d by the caspase 3 inhibitor, Z-DEVD-FMK. Mitochondrial permeability that o ccurred was also increased during this induction of apoptosis. Bongkrekic a cid, a mitochondrial membrane stabilizer, inhibited DEM-induced apoptosis. The inhibitors' effects of LPS or GM-CSF on spontaneous neutrophil apoptosi s was reversed by DEM, which was mediated by an increase in caspase 3 activ ity and independent of mitochondrial disruption. Caspase activation is an i mportant step in glutathione depletion-induced apoptosis in resting and inf lammatory neutrophils. Regulation of caspase activity may represent a possi ble target to trigger apoptosis and resolve inflammatory disorders.